EJ20G Swap Questions

[MConte05]

Believe me, I've tried searching. Lots of good general information, but tough to nail down these specific questions.

1991 Subaru Legacy Turbo

Current setup:
RobTune 440
Running on an EJ20G ECU
4-to-2 ignitor conversion
440cc injectors

The 2.2T in the rally car ended up having the thrust bearing decide to leave completely, letting the crankshaft move in and out over a quarter inch. In typical 22T fashion I still ran an entire race like this with full boost and won day 1, and setting top 6 stage times nationally out of 60+ cars that were entered at STPR 2015. It's making a racket, but clean oil. So I am deciding to pull it before it leaves me stranded on the side of a stage road and out my entry fee!

Enter in the 1995 WRX EJ20G that just arrived yesterday. I am putting a TD04HLA-19T twinscroll turbo on there, converting the fuel system, PS pump, and coolant crossover pipe to run a custom turbo inlet. A lot of stuff on my engine is race only, hardly any vacuum lines, no BPV return, etc. So the inlet is just aluminum pipe going to the turbo restrictor, and will have a single port for the IAC to plug in.'

Long story short. I have a good clean 1995 WRX engine harness. What is going to need to be done to get it to work well with my 1991 Turbo engine bay harness?

Specific questions are:

1. What do I do about my ignitor setup? Does the 4-to-2 converter do the job of letting me run the COP on the WRX engine? Do I need to undo the converter and find a 2 channel ignitor?

2. Beside the coolant temp sensor extension, is there any additional wiring I'll need to be prepared to do given that I've already been running an EJ20G ecu on the previous engine?

Pretty excited to get this thing in, especially with the twin scroll setup. Be sure to check out TeamConte on facebook to see more progress pictures and videos!

facebook.com/teamconte

[cj91legss]

Checked & Liked.

Can you get your hands on a set of 02-05 coil packs? You could run the 4 ignition wires right off the ecu to the packs. I don't think you can use the 20G engine harness without having both diagrams in front of you and laying them out to verify wires. Your quickest solution would be to swap the harness from the bad engine to the new engine.

[MConte05]

Would like to keep from having random wires going all over the place. So solid connectors on the coilpacks is ideal.

[cj91legss]

That makes sense, you'll just have to skim the engine harness diagrams. Are the plugs the same by the driver's side strut tower?

[Alphius]

EJ20G coilpacks are notoriously unreliable. You might want to rethink either swapping to WRX coils or using the factory EJ22T wasted spark setup.

If you run wasted spark, it is a drop-in swap aside from figuring out how to mount the coilpack on the IM. If you swap to coil on plug you will need to run wires from the ECU to the coilpacks somehow. If you go this route, the 4-2 converter will be removed from the system.

The EJ22T engine harness is nearly perfect layout for the EJ20G, but if you want to use the EJ20G engine harness you may need to repin the ends to get it to connect to your body harness. I'm not so sure about this because I've only ever reused the EJ22T engine harness and kept the wasted spark coilpack.

[TurnNburn]

Everything Alphius said is spot on. Wasted spark is definitely easiest to get running, but converting to COP is the way to go. (without 20G coils, unless you have a few spares)

[MConte05]

So is there any performance or reliability benefit to going to COP vs wasted spark? I've got access to a lot of IM's that I can use (including some EJ20Ks) so getting one mounted up shouldn't be an issue.

I've also got access to a lot of WRX coilpacks, so that's also not a problem. Wiring I don't mind doing as long as it can be a reliable setup that is well protected and robust. This thing sees extreme abuse compared to a typical street car.

[TurnNburn]

COP creates more voltage before discharging creating a hotter spark, which in theory makes a more complete and reliable burn which equals more power. How much more? Hard to say. But if you have the parts laying around and aren't afraid of a wiring diagram I say go for it!

[PhyrraM]

This is clear in my mind, hopefully it translates to text intact.....

Easiest and most immediate reliability for a race car..EJ22T engine harness and wasted spark coilpack. The only challenge is mounting the coilpack and possibly custom length plug wires. I suggest where the A/C compressor was.

EJ20G COP coils? Pass! Not considered reliable, crack easily. The root cause of many blown engines for two decades.

GD+ coils are the ultimate way to go. They have built in igniters, so all the factory igniters and the 2-4 channel adapter igniters go away. They have 3 pins each. One is for the ground, one is for +12V (ignition), the last simply goes to the ECU pin for that cylinder. I, personally, would start with either an EJ20G or EJ22T engine harness and modify it to suit (essentially make a new, custom harness by using parts of the old).

[MConte05]

That's what I have decided to do. Found a great guide on wiring up GD coils. Doesn't seem that tough at all. Will just get quality connectors.

Already have worked up a way to use the stock fuel rail and get a turbo intake under the inlet manifold using the EJ20G intake without giant spacers. Just switching to a WRX power steering pump as well. FMIC along with a lot of DEI thermal control products means that it should be a pretty slick motor soon.